1. Field of the Invention
The present invention relates to a method of communication between a processor and an external device, and to a processor employing this method of communication.
2. Description of the Related Art
Japanese Unexamined Patent Application Publication No. 5-336296 discloses a communication method in which the functions of a communication terminal such as a facsimile machine are set up according to values sent through an interface that connects the terminal to a host computer.
Japanese Unexamined Patent Application Publication No. 6-46103 discloses a communication method in which, upon reception of data according to a predetermined protocol, a central processing unit (CPU) sends a direct memory access (DMA) request signal to a DMA controller, which then transfers data between a memory device and a communication device without CPU intervention.
In conventional communication methods such as these, when a processor transmits internal data to an external device, or receives data from an external device, it is first necessary to set configuration data, such as data specifying the data communication speed or bit rate, in both the external device and the processor's data communication interface. Both settings are conventionally carried out by the processor's CPU, but this places an undesirable burden on the CPU, particularly when the configuration data have to be set frequently.